72. Relation Between Biological Stress Reactivity and Behavioural Reward Responsivity in Major Depressive Disorder

Recent theoretical and empirical work suggests that reactivity to threat and responsivity to reward constitute correlated domains of functioning. The goal of the current study was to examine the extent to which depression status and gender act as moderators of the relation between these two systems. Participants included 127 adults recruited from the community (age 18-65; 56 women; 73 with a current diagnosis of major depression). Salivary cortisol was assayed at 8 time points to assess reactivity to the Trier Social Stress Task (TSST). Reward responsivity was assessed behaviourally using the Probabilistic Reward Task (PRT). Results indicated that in non-depressed men only, both higher total cortisol output and quicker return to baseline (greater recovery), were associated with greater reward learning. These results are consistent with a small number of previous studies suggesting that healthy men in particular display a rapid mobilization and recovery of cortisol during stress that may optimize responsivity to reward. In contrast, again only in men, higher total cortisol output was associated with lower response bias to the rewarded stimulus. Results are discussed in terms of implications for theories of gender differences in the development of MDD as well as differences across phases of reward processing.